This invention relates to a vehicle driven by a motor (fuel cell vehicle, series hybrid vehicle) wherein electrical energy is generated using fuel, and this electrical energy is used to drive the motor.
JP-A-H9-7618 published by the Japanese Patent Office in 1997 discloses a method wherein a running load of a fuel cell of a fuel cell vehicle is determined based on the average value of the electrical load of the vehicle. This method aims to reduce the capacity of the battery mounted on the vehicle to conserve the power generated by the fuel cell, and lower the response required of the fuel cell.
However, in an approach where the running load of the fuel cell is decided based on the average value of electrical load, when the motor is regenerating power during vehicle deceleration or on a downward slope, it frequently occurs that the fuel cell system also generates power under a high running load. In such a situation, the sum of regenerated power and generated power becomes excessive, so the power cannot be completely stored by the battery or the battery electrodes may deteriorate due to overcharging.
In particular, in a situation where the brakes are fully applied from the state where the vehicle was running near the maximum rated load, it is necessary to charge the battery simultaneously with the maximum generated power and the maximum regenerated power, and if the battery capacity is set to comply with these requirements, the size of the battery will be increased, costs will rise and it will be more difficult to install the battery on the vehicle.
It is therefore an object of this invention to correct the running load calculated from the electrical load value according to the regenerated power, avoid enlargement of the battery, and perform power management efficiently.
In order to achieve above object, this invention provides a vehicle drive system, comprising a power generation device which generates power using fuel, a battery which stores power generated by the power generation device, a rotating machine which drives the vehicle using power supplied from the power generation device and battery, and regenerates power when the vehicle is decelerating, and a controller which functions to compute a smoothed value of an electrical load of the vehicle, compute a running load command value supplied to the power generation device based on the smoothed electrical load value, determine the regeneration state of the rotating machine, correct the running load command value based on the regeneration state of the rotating machine, and control the power generation device based on the corrected running load command value.